1. Field of the Invention:
The present invention relates to a space truss, a precast reinforced concrete slab reinforced by the space truss; a modified space truss or reinforcing member for reinforcing the concrete slab, the reinforcing member being composed of the space truss, a hanging hook suspended from the space truss and a sheet-steel formwork suspended from the hanging hook; and a modified precast reinforced concrete slab in which are embedded the space truss, hanging hook and the sheet-steel formwork. The space truss is constructed of a pair of plane trusses which is oppositely disposed from each other and fixedly connected with each other so as to be formed into the space truss. The space truss is embedded in concrete to form the precast reinforced concrete slab.
2. Prior Art
Hithereto, in order to reinforcing a precast concrete slab serving as a concrete floor and a concrete wall, conventional trusses are embedded in the precast concrete slab. A first one of the conventional trusses is composed of an upper and a lower chord member assembled in three dimensions; and strut members welded to the thus assembled three-dimensional chord members to form a space truss. A second one of the conventional trusses is composed of chord members lying in a single plane; and strut members welded to such chord members in the single plane to form a plane truss which is then symmetrically bent along its one of the chord members to form a space truss in which the one of the chord members serves as an upper chord member of the space truss. However, as for the first one of the trusses, it is necessary to weld the strut members to the chord members after the chord members are assembled in three dimensions. On the other hand, as for the second one of the trusses, it is necessary to bent the plane truss after the strut members are welded to the chord members. As described above, any of the first and the second one of the trusses requires a difficult working in manufacturing thereof, and, therefore has a fear that the thus completed space truss is poor in dimensional accuracy. Particularly, any of the conventional trusses substantially provides a single reinforcing steel bar extending from an upper surface of the precast reinforced concrete slab when embedded in the concrete slab. Consequently, the precast concrete slab reinforced by the conventional space truss lacks structural strength, and, therefore makes it impossible that construction workers effectively perform their works on the precast reinforced concrete slab. In order to resolve these problems, in the conventional precast concrete slab, the space trusses are closely embedded in the concrete slab so as to extend in a width direction of the slab, or intersect with each other at right angles in the slab. However, such embedding work of the conventional space trusses is very cumbersome. Particularly, in the construction field, such embedding work is very poor in workability.